1. Field of the Invention
This invention relates to the actuation of read/write heads in data storage systems. More particularly, this invention relates to the linear actuation of read/write heads in relatively high density data storage configurations by using a compound parallel bendable element suspension system and driving means assembled therewith.
2. Description of Related Art
In disk file data recording systems, linear actuation of read/write heads in the direction of the disk radius is the desired mechanism for accessing data tracks. In lower track density disk file systems, rotary actuators, which translate the read/write heads, non-linearly, through an arc are acceptable and used. In higher track density disk file systems, highly accurate, linear actuators, such as voice coil motors, are required. These highly accurate, linear actuators require elaborate bearing assemblies, guides, etc. to effect their linear motion. Heretofore, there has not been a simple, cost effective means by which highly accurate, linear track actuation has been attainable.
While simple parallel spring suspensions have been used to provide head actuation (see, for example, U.S. Pat. No. 3,531,126 issued to Tsukagoshi), these devices are known to introduce skew angle errors (rotation of the head relative to track) when used with magnetic recording heads.
For example, when a deflection force perpendicular to the leaf spring is applied to the movable head end of a parallel leaf spring suspension, skew angle errors occur because of the shortening of springs. As the movable head end is translated across the disk file, the effective length of the springs is reduced which shifts the location of the head in relation to the tracks on the disk file (see for example, U.S. Pat. Nos. 4,374,402; 4,188,645; 3,702,192; 3,634,309; and 3,531,126). These skew angle errors make simple parallel spring suspension systems unacceptable for high density recording disk files.
While compound parallel spring suspensions are known, heretofore, such spring suspensions have not been used in data storage applications. While such spring suspensions are known not to have problems with skewing, problems of accurate translation in driving the load and problems of harmonic oscillations of the suspension have caused such spring suspensions to be regarded as unsuitable for read/write head actuation disk files.
It is therefore an object of the present invention to provide for a simple, cost efficient, highly accurate linear translation device for use with high density recording disk files.